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#17 Add credit_card_luhn generater #26

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#17 Add credit_card_luhn generater #26

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53 changes: 51 additions & 2 deletions src/payment.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -26,8 +26,38 @@ pub fn credit_card_number() -> String {
}

pub fn credit_card_luhn_number() -> String {
// @TODO
return String::from("");
let mut cc_str = credit_card_number();
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What do you think writing the algorithm of luhn generation? I think it's much nicer solution to write the function on the way that it generates a proper luhn number sequence for the first run.

Resources:

Let me know your thoughts. :)

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Yeah, I absolutely think that is the right way to go. I only did it this way because I was trying to stay close to the go fakeit library, but if you're cool diverging a bit, then generating the last digit is much better and potentially future-usable than guess-and-check.

Will change.

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Yes, I'm not a big fan of how gofakeit solves it, so that would be awesome if you could have change it. Thank you.

let mut cc_num = cc_str
.parse::<u64>()
.expect("generated bad credit card number");

// iterate until you hit a cc number that passes the luhn check
while !is_luhn(&cc_str) {
cc_num += 1;
cc_str = cc_num.to_string();
}

cc_str
}

// is_luhn check is used for checking if credit card is a valid luhn card
fn is_luhn(cc_str: &String) -> bool {
let parity = cc_str.len() & 1;
let mut sum = 0;
for (i, ch) in cc_str.chars().enumerate() {
let Some(digit) = ch.to_digit(10) else {
return false;
};

if i & 1 != parity {
sum += digit;
} else if digit > 4 {
sum += digit * 2 - 9;
} else {
sum += digit * 2;
}
}
sum % 10 == 0
}

pub fn credit_card_exp() -> String {
Expand Down Expand Up @@ -69,6 +99,25 @@ mod tests {
});
}

#[test]
fn is_luhn() {
exec_mes("payment::is_luhn", || {
(if payment::is_luhn(&"4716685826369360".to_string()) {
"luhn"
} else {
""
})
.to_string()
});
}

#[test]
fn credit_card_luhn_number() {
exec_mes("payment::credit_card_luhn_number", || {
payment::credit_card_luhn_number()
});
}

#[test]
fn credit_card_exp() {
exec_mes("payment::credit_card_exp", || payment::credit_card_exp());
Expand Down